What is ICD-10 code M05.89?

M05.89 is the ICD-10-CM diagnosis code for Other rheumatoid arthritis with rheumatoid factor of multiple sites. Rheumatoid arthritis with rheumatoid factor affecting multiple joints throughout the body simultaneously. It belongs to the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99). M05.89 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. M05.89 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. M05.89 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. M05.89 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does M05.89 map to under V28?

M05.89 maps to CMS-HCC V28 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders). The category number and label come from the CMS-HCC V28 model file for payment year 2026.

What does M05.89 pay in RAF?

M05.89 carries a community, non-dual, aged (CNA) RAF weight of 0.617 under CMS-HCC V28 for payment year 2026. The weight comes from the CMS V28 relative-factor file, not a hand-typed table.

What is the V28 vs V24 difference for M05.89?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For M05.89, V28 maps to Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders at RAF 0.617 while V24 mapped to Rheumatoid Arthritis and Inflammatory Connective Tissue Disease at RAF 0.421. Both models can still appear in legacy data and in payer-specific lookback periods.

2026 ICD-10-CM M05.89: Other rheumatoid arthritis

M05.89 maps to CMS-HCC V28 93 (RAF 0.617). Documentation must support MEAT. MEAT criteria · RAF calculator · HCC coding software

ICD-10-CM Code View

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Code lookupM05.89Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Inflammatory polyarthropathies (M05-M14)

M05.89

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Other rheumatoid arthritis with rheumatoid factor of multiple sites

Rheumatoid arthritis with rheumatoid factor affecting multiple joints throughout the body simultaneously.

Buddy Insight

CMS-HCC V28

Mapped

HCC 93

Rheumatoid Arthritis and Othe...

RAF 0.617

CMS-HCC V24

Mapped

HCC 40

Rheumatoid Arthritis and Infl...

RAF 0.421

ACA/HHS

Mapped

HCC 56

HHS-HCC 56

Varies by metal level

ESRD/PACE

Mapped

HCC 40

Rheumatoid Arthritis and Infl...

RAF 0.058

RXHCC

Mapped

HCC 83

Rheumatoid Arthritis and Infl...

RAF 0.222

Code Book Path

Official

M05Rheumatoid arthritis with rheumatoid factor

M05.8Other rheumatoid arthritis with rheumatoid factor

M05.89Other rheumatoid arthritis with rheumatoid factor of multiple sites

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for M05.89 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for M05.89 in this effective period.

Related Child Codes

Official

M05.80Other rheumatoid arthritis with rheumatoid factor of unspecified site

M05.81Other rheumatoid arthritis with rheumatoid factor of shoulder

M05.82Other rheumatoid arthritis with rheumatoid factor of elbow

M05.83Other rheumatoid arthritis with rheumatoid factor of wrist

M05.84Other rheumatoid arthritis with rheumatoid factor of hand

Includes

Official

ICD-10-CM does not list Includes notes for M05.89 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for M05.89 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for M05.89 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for M05.89 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for M05.89 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Clinical diagnosis of rheumatoid arthritis clearly documented by the treating provider

Rheumatoid factor lab result status (positive or negative) consistent with the code selected

Affected joint(s) specified with laterality (right, left, or bilateral)

Current disease status: active, in remission, or chronic stable

MEAT Support

HCC Buddy guidance

Clinical diagnosis of rheumatoid arthritis clearly documented by the treating provider

Rheumatoid factor lab result status (positive or negative) consistent with the code selected

Affected joint(s) specified with laterality (right, left, or bilateral)

Current disease status: active, in remission, or chronic stable

Audit Caution

HCC Buddy guidance

Failing to verify rheumatoid factor status before selecting between M05 (seropositive) and M06 (seronegative) categories — lab results must support code selection

Coding rheumatoid arthritis based solely on a positive rheumatoid factor lab result without a clinical diagnosis from the provider — a positive rheumatoid factor alone is not sufficient to code rheumatoid arthritis

Reporting rheumatoid arthritis from past medical history without confirmation that the condition is still active, being treated, or being monitored during the current encounter

Using the 'multiple sites' code instead of coding each specific joint site individually — individual site codes provide greater specificity for risk adjustment

Common Mistakes

HCC Buddy guidance

M05.7xx (Rheumatoid arthritis with rheumatoid factor without organ involvement, same site) — Use M05.7xx for the standard seropositive presentation without organ or systems involvement

M06.0xx (Rheumatoid arthritis without rheumatoid factor, same site) — Use M06.0xx when rheumatoid factor is negative

M06.9 (Rheumatoid arthritis, unspecified) — A nonspecific code that does not indicate rheumatoid factor status; avoid when rheumatoid factor status is known

M05.0x-M05.6x (Rheumatoid arthritis with organ involvement such as Felty syndrome, rheumatoid lung, vasculitis) — Use these when extra-articular manifestations are documented

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is M05.89 an HCC code?

Yes. M05.89 (Other rheumatoid arthritis with rheumatoid factor of multiple sites) maps to Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders under the CMS-HCC V28 risk adjustment model (and Rheumatoid Arthritis and Inflammatory Connective Tissue Disease under V24), with a community non-dual aged RAF of 0.617. It is billable for payment year 2026.

Coder answer: M05.89 is billable and maps to V28 HCC 93, Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: M05.89
Description: Other rheumatoid arthritis with rheumatoid factor of multiple sites
HCC (V28): HCC 93 — Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders
RAF: 0.617
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 93, Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders

0.617

V24HCC 40, Rheumatoid Arthritis and Inflammatory Connective Tissue Disease

0.421

ESRDHCC 40, Rheumatoid Arthritis and Inflammatory Connective Tissue Disease

0.058

RxHCCHCC 83, Rheumatoid Arthritis and Inflammatory Connective Tissue Disease

0.222

Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

Work M05.89 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for M05.89

For M05.89 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed M05.89 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

M05.89 is the ICD-10-CM diagnosis code for other rheumatoid arthritis with rheumatoid factor of multiple sites. Rheumatoid arthritis with rheumatoid factor affecting multiple joints throughout the body simultaneously. M05.89 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering inflammatory polyarthropathies (m05-m14).

Under the CMS-HCC V28 risk adjustment model, M05.89 maps to Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders (HCC 93) with a community, non-dual, aged base RAF weight of 0.617. Under the older CMS-HCC V24 model, M05.89 maps to Rheumatoid Arthritis and Inflammatory Connective Tissue Disease (HCC 40) with a community, non-dual, aged base RAF weight of 0.421. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

This code is used when rheumatoid arthritis involves three or more different joint sites. Because M05.89 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for M05.89 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This code is used when rheumatoid arthritis involves three or more different joint sites
•Document all affected sites in the medical record to support polyarticular disease coding

Clinical Significance

This code captures other specified manifestations of seropositive rheumatoid arthritis with positive rheumatoid factor, representing a systemic autoimmune condition with potential for progressive joint destruction and disability. Accurate capture is essential for risk adjustment as it reflects significant ongoing treatment burden including disease-modifying antirheumatic drugs, biologics, and regular laboratory monitoring.

Documentation Requirements

✓Clinical diagnosis of rheumatoid arthritis clearly documented by the treating provider
✓Rheumatoid factor lab result status (positive or negative) consistent with the code selected
✓Affected joint(s) specified with laterality (right, left, or bilateral)
✓Current disease status: active, in remission, or chronic stable
✓Current treatment plan including medications (disease-modifying antirheumatic drugs, biologics, nonsteroidal anti-inflammatory drugs)
✓Specification of the 'other' rheumatoid arthritis manifestation or feature that distinguishes it from standard presentations
✓Documentation of each specific joint involved; consider coding each site individually if clinically distinct
✓Assessment and plan addressing rheumatoid arthritis at each encounter where it impacts care or treatment

Commonly Confused Codes

•M05.7xx (Rheumatoid arthritis with rheumatoid factor without organ involvement, same site): Use M05.7xx for the standard seropositive presentation without organ or systems involvement
•M06.0xx (Rheumatoid arthritis without rheumatoid factor, same site): Use M06.0xx when rheumatoid factor is negative
•M06.9 (Rheumatoid arthritis, unspecified): A nonspecific code that does not indicate rheumatoid factor status; avoid when rheumatoid factor status is known
•M05.0x-M05.6x (Rheumatoid arthritis with organ involvement such as Felty syndrome, rheumatoid lung, vasculitis): Use these when extra-articular manifestations are documented
•M19.x (Osteoarthritis): Osteoarthritis is a degenerative, non-autoimmune condition; do not confuse with rheumatoid arthritis which is inflammatory and autoimmune